refactor: move methods into a contract test trait

tests/EventRepositoryContractTest.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace App\Tests;
+
+use App\EventRepository;
+
+trait EventRepositoryContractTest
+{
+    private EventRepository $repository;
+
+    /** @test */
+    public function should_only_return_attendees_with_a_yes_rsvp(): void
+    {
+        $attendees = $this->repository->getConfirmedAttendees();
+
+        $this->assertCount(3, $attendees);
+    }
+
+    /** @test */
+    public function should_not_return_event_organisers(): void
+    {
+        $attendees = $this->repository->getConfirmedAttendees();
+
+        $this->assertCount(3, $attendees);
+    }
+}